Internal combustion engine



Oct. 23, 1934. M. WOOLSON 1,978,333

INTERNAL COMBUSTION ENGINE Filed 001:. 1, 19:50

Patented Oct. 23,

f UNITED STATES PATENT OFFICE V I 1,978,322 v INTERNAL coMBus'rIoN ENGINE Lionel M; Woolson, deceased, late of Detroit,

Mich., by Emma F. Woolson, executrix, Bloomfield Village,-l\Iich., assignor to Packard Motor Car Company, Detroit, Mich., a corporation of Michigan I L Application October 1,

9 Claims.

This invention relates .to cam followers and particularly to cam followers and associated mechanism for .use on internal combustion engines or wherever there is a possibility of a reverse rotation of the cam. V

i It is a general object of the present invention to provide a novel and .improvedcam follower mechanism. i r v i More particularly, it is an object of .the invention to provide a cam follower and associated mechanism for use with cams having a step or abruptfacefor the prevention of breakageiofthe follower incase of reverse rotationof the cam.

. An i-mportantfeature of thexinvention resides in the arrangement of a cam follower so mounted that the resilient means used to bias the followerwtoward the .cam'also maintains the cam follower in its normal position but-permits it to rotate clear of the step of the cam in the event of reverse rotation to preventthe cam step from breaking the follower; i Other and further objects and featureslof the invention will be understood by those skilled in the art from a consideration of the-accompany ing drawing and following specification wherein is disclosed an embodiment of the invention adapted for usew-ith internal combustion enginesoperating onthe' Diesel cycle.- It will be understood that, although 'the invention is illustrated in this particular embodiment, it is limited onlywby the scope of the appended claims;

The single figureof the drawingillustratesa transverse sectionof an internal combustion engine including fuel injection mecha'nism operated with apparatus constructed according to the present invention. 1 1

In the operation of cams of the type which may be known as stepped or stew cams, wherein there is 'an abrupt face, often radial, it is necessary to insure that the cam rot-atesal-ways ins'uch-a direction that thefollower drops off of the step or to provide means whereby'the follower can 'be moved out of the way bythe re- 1930, serial no. 485,735

nism. Such a fuel injection system is disclosed and claimed in the copending application of Lionel M. Woolson, for Internal combustion engines,:flled April 29, 1929; Serial No. 358,899.,

Briefly, the fuel injection system comprises a fuelpump 10 arranged to discharge fuel through a nozzle 11 into thev space 12 above the piston 13 in the cylinder 14 of an internal combustion engine. The plunger 15 of this fuel pump is lifted or projected upwardly to compress the fuel and inject it into the cylinder, and is retracted so that its end 16 is below the fuel inlet ports 17 for the purposeof receiving a charge of fuel. It is highly desirable that the charge be injected suddenly into the chamber and that it be of constant quan- 26 slidable in a guide 27 mounted in the crankcase and having its upper end bearing adjustably on the lower end of the pump plunger which is retained in engagement therewith by means of the return spring 29. Adjustment of the stroke or the pump plunger is'effected by moving the end 24 of the strut in the groove 23 toward or from the pivotof the bell crank lever by means of the link 30 and other mechanism which is unnecessary todescribe.

The" second arm 36 of the bell crank lever 26 is provided at its end with a follower 37 which bears on theperiphery of a cam 33 mounted on a shaft 34 parallel to-the shaft 21 of the bell crank leveri- The arms of the bell crank lever straddle the eam, andthe shaft of the cam is parallel to the shaft of the bell crank lever. Of course, the

:cam shaft is driven intimed relation to the movement of the piston in any of the conventional ways: I? V a i The cam is what may betermed astepped one in that its"surface from the point of least radius to the point ofmaXimuni'radius is" smooth and of substantially uniform lift, but there is a sharp step composed of a substantially radial face connecting'the points of minimum and maximum-radius; The carn rotates in thedirection indicatedby the arrow so that the follower drops off of the step. If, however, there-should be a reversal of rotation of the cam," as may happen during the starting operation or when the engine has the tip 39, which rides on the cam periphery,-

and the shoulder 40, which in normal operation engages the shoulder 41 on the arm 36, as clearly seen in the drawing.

In order to maintain the shoulders 40 and 41 in engagement during normal operation, a spring is arranged to exert pressure on the arm 42 of the cam follower to press the shoulders together, and this spring will give way if the cam reverses and allows the shoulders to be separated and the follower to flip out of the wayof the step 43 on the cam. Q

The spring which performs this function can also be made to be the trigger or actuating spring for the pump plunger and in the present instance is shown as a large helical spring 45, surrounding a stem 46 having a portion 47 loosely, and slidably mounted in a guide .plate 48 carried on a part 49 secured to the crankcase. This part 49 in: cludes a separate ring and removable cover plate, of which the ring carries the bearing member 50 for the bell crank lever shaft and provides bear,- ings for the shaft 51 which adjusts the stroke of the pump. One end of the spring 45 bears beneath the guide plate 48, and the other end bears on a collar 52 secured near the opposite end of the stem 46. The actual end 53 of the stem is rounded and bears ina notch 54 in the rear face of the cam follower arm 42. There is a guide lug 55 formed integral with the arm 36 of the bell crank lever and perforated to guide the tip 53 of the spring spindle to prevent it from being moved out of the notch 54 when the follower is flipped by a reversal of the cam.

It will be noted that the spring 45 suppl es not only the motive power for operating the pump p un er w en th o ow r drops ff of h st p of the cam, but it maintains the follower in its normal position as well as presses the follower and its lever always against the cam. The spring 45 must be of superior strength to that o t spr o t e o u pose he p n 29 is to return the plunger and to make it follow the movement of the strut and cross-head 26. In performing this triple function, the spring 45 has ne of s ends b a i a ns a st i ar ab tment and the other against a lever movable about its own pivot which in turn is carried about a second pivot.

It will be obvious from the description of the construction of the spring mechanism and the cover plate that the cover plate can be removed independently of the ring whichcarries the pivot for the bell crank lever and the pump stroke adjusting lever and willcarry with it the spring 45 and the spring stem 46 as a unit, for the head on the stem bearing against the guide plate 48 will prevent the spring from withdrawing the stem from the guide. Thus the spring will remain under slight tension'on the removal. Of course, the end of the stem will slide out of the guide 55 on the lever 36 as the cover plate is withdrawn. This permits aninspection of all of the parts remaining in position without having them under tension from the spring and also permits an inspection or renewal of the spring without disassembling any other parts of the mechanism Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a mechanism for operating a translating device by spring pressure including a driven shaft having a step earn, the combination of a lever pivoted adjacent said cam and having one arm operatively associated with said device, a cam follower pivoted to another arm of said lever and bearing on said cam, a shoulder on said last mentioned arm normally engaged by said follower, a spring adapted to supply the effort necessary to actuate said device, said spring bearing on said follower to hold it against said shoulder and against the cam, reverse movement of said cam moving the follower from the shoulder and flexing said spring.

2. In a mechanism for operating a translating device by spring pressure including a driven shaft having a step cam, the combination of a lever pivoted adjacent said cam and having one arm operatively associated with said device, a cam follower pivoted to another arm of said lever and bearing on said cam, a shoulder on said last mentioned arm normally engaged by said follower, a spring to bias the follower against said cam and to actuate said device when the follower drops off of the cam step, said spring acting on the follower to hold it against said shoulder except when upon reversal of the cam shaft the step face engages the follower.

3. In a mechanism for operating a reciprocating translating device by spring pressure including a driven shaft having a step cam, the combination of a lever pivoted adjacent said cam, means to maintain said .device .in operativerelation to one arm of said lever, a cam follower pivoted to one arm of said lever in such a manner thatit can swing out of the way. of the step upon reversal of said cam, a shoulder on said last mentioned arm abutted by said follower in normal operation, an extension on said follower beyond its pivot and an operating spring for said device having a stationary end and an end cooperating with said extension.

4. In a mechanism for operating a translating device, the combination of a cam shaft with a step cam, the combination of a bell crank lever pivoted adjacent and with its arms straddling said cam, means associating the device and one arm of said lever, a cam follower pivoted to the other arm of said lever and extending substantially radially of the cam, resilient means biasing the lever to actuate the device as the follower moves down the step and meansto flex the resilient means upon reverse movement of the cam.

5,. Operating mechanism for a translating device comprising a cam having an abrupt step, a lever pivoted adjacent said cam and in operative relation to sa de i e, a ollo er r ed by sai leve me ns. t bia e l ver to ct e-tho evice. aid mea al i i th llo r ain ai m n ean vo in said llo er or mo em nt o a a d ia on n gement y the step face on reversal of the cam, to prevent b ea age, Y 7

6. Operat n me han m fo a an l tin d vic omp sin a a hav n v a ab p, a eve i ot diaoon t a am an i ope at v r ion o the dev e. a com llo bearin n Said a moa s pi s d f l to said l er on an ax para l o h m xi a shou de o a d ov en a e y Said-fol ow to limit movement of the follower in the direction o mo ment oilood b Properot ion o the cam step.

7. Operating mechanism for a translating device comprising a cam having an abrupt step, a lever pivoted adjacent to said cam and in operative relation to the device, a cam follower bearing on said cam, means pivoting said follower to said lever on an axis parallel to the cam axis, a shoulder on said lever engaged by said follower to limit movement of the follower in the direction of movement caused by proper rotation of the cam, an extension on said follower beyond the pivot, a spring pressed stem bearing on said extension, said stem biasing the follower against said shoulder and the lever toward the cam to operate the device when the follower drops off of the cam step and a projection on said lever adjacent said extension having a hole therein, the Walls of which guide and position said stem.

8. A follower mechanism for a stepped cam including a pivoted lever, a cam follower pivoted to said lever, a shoulder on said lever normally abutted by the follower, spring means urging the follower against the shoulder and the lever toward the cam, saidmeans including a stem bearing on said follower, a cover plate for the mechanism having an aperture for the passage of the stem, a head on the stem outside of the cover plate, a collar on said stem near the follower and a coil spring surrounding the stem and compressed between the collar and cover plate, whereby the cover plate, spring and stem are remov able as a unit.

9. A follower mechanism for a stepped cam in? cluding a pivoted lever, a cam follower pivoted to said lever, a shoulder on said lever normally abutted by the follower, spring means urging the follower against the shoulder and the lever toward the cam, said means including a stem bearing on said follower, a guide for the opposite end of said stem, an abutment near the follower end of the stem, a coil spring surrounding the stem and compressed between the abutment and guide and a guide for said stem carried by said lever.

EMMA F. WOOLSON, Erecut' riw of the Estate of Lionel M. Woolson,

Deceased. 

